Apparatus, system and method for an additive manufacturing print head

ABSTRACT

The disclosure is of and includes at least an apparatus, system and method for a print head for additive manufacturing. The apparatus, system and method may include at least two proximate hobs suitable to receive and extrude therebetween a print material filament for the additive manufacturing, each of the two hobs comprising two halves, wherein each of the hob halves comprises teeth that are offset with respect to the teeth of the opposing hob half; a motor capable of imparting a rotation to at least one of the two hobs, wherein the extrusion results from the rotation; and an interface to a hot end capable of outputting the print material filament after at least partial liquification to perform the additive manufacturing.

RELATED APPLICATIONS

This application is a continuation application of application Ser. No.17/479,112, entitled: APPARATUS, SYSTEM AND METHOD FOR AN ADDITIVEMANUFACTURING PRINT HEAD, filed Sep. 20, 2021; which is a continuationapplication of application Ser. No. 17/176,078, entitled: APPARATUS,SYSTEM AND METHOD FOR AN ADDITIVE MANUFACTURING PRINT HEAD, filed Feb.15, 2021, which is a continuation application of application Ser. No.16/902,872, entitled: APPARATUS, SYSTEM AND METHOD FOR AN ADDITIVEMANUFACTURING PRINT HEAD, filed on Jun. 16, 2020, which is acontinuation application of application Ser. No. 16/687,363, entitledAPPARATUS, SYSTEM AND METHOD FOR AN ADDITIVE MANUFACTURING PRINT HEAD,filed on Nov. 18, 2019, which is a continuation application ofapplication Ser. No. 15/723,856, entitled APPARATUS, SYSTEM AND METHODFOR AN ADDITIVE MANUFACTURING PRINT HEAD, filed Oct. 3, 2017, thecontents of which is incorporated by reference in their entiretiesherein.

BACKGROUND Field of the Disclosure

The present disclosure relates to additive manufacturing, and, morespecifically, to an apparatus, system and method for an additivemanufacturing print head.

Description of the Background

Additive manufacturing, including three dimensional printing, hasconstituted a very significant advance in the development of not onlyprinting technologies, but also of product research and developmentcapabilities, prototyping capabilities, and experimental capabilities,by way of example. Of available additive manufacturing (collectively “3Dprinting”) technologies, fused deposition of material (“FDM”) printingis one of the most significant types of 3D printing that has beendeveloped.

FDM is an additive manufacturing technology that allows for the creationof 3D elements on a layer-by-layer basis, starting with the base, orbottom, layer of a printed element and printing to the top, or last,layer via the use of, for example, heating and extruding thermoplasticfilaments into the successive layers. Simplistically stated, an FDMsystem includes a print head from which the print material filament isfed to a heated nozzle, an X-Y planar control form moving the print headin the X-Y plane, and a print platform upon which the base is printedand which moves in the Z-axis as successive layers are printed.

More particularly, the FDM printer nozzle heats the thermoplastic printfilament received from the print head to a semi-liquid state, anddeposits the semi-liquid thermoplastic in variably sized beads along theX-Y planar extrusion path plan provided for the building of eachsuccessive layer of the element. The printed bead/trace size may varybased on the part, or aspect of the part, then-being printed. Further,if structural support for an aspect of a part is needed, the traceprinted by the FDM printer may include removable material to act as asort of scaffolding to support the aspect of the part for which supportis needed. Accordingly, FDM may be used to build simple or complexgeometries for experimental or functional parts, such as for use inprototyping, low volume production, manufacturing aids, and the like.

However, the use of FDM in broader applications, such as medium to highvolume production, is severely limited due to a number of factorsaffecting FDM, and in particular affecting the printing speed, quality,and efficiency for the FDM process. As referenced, in FDM printing it istypical that a thermoplastic is extruded from the print head, and thenheated and pushed outwardly from a heating nozzle, under the control ofthe print head, onto either a print plate/platform or a previous layerof the part being produced. The nozzle is moved about by the robotic X-Yplanar adjustment of the print head in accordance with a pre-enteredgeometry, such as may be entered into a processor to control the roboticmovements to form the part desired.

Thus, current limitations on the cost, efficiency, and performance ofadditive manufacturing often occur due to the nature of known printheads, such as those print heads typically provided in FDM printing. Inshort, in a typical known print head, print material is fed from a spoolthrough two print hobs that serve to extrude the print material towardthe “hot end” of the printer. In known embodiments, a stepper motorturns both adjoining hobs having the print material therebetween inopposite directions in order to feed the print material from the spoolto the hot end. However, the step-wise nature of current print materialfeeds often scores the filament, and further subjects the print materialfilament to various undesirable effects, such as compression, friction,and lag. Lagging of the print material may be particularly detrimental,at least in that the print material may curl or otherwise re-spool atthe output from or input to the hobs, thereby jamming the printer. Thenature of the hobs presently in use exacerbates these adverse printingeffects.

Therefore, the need exists for an apparatus, system, and method for anadditive manufacturing print head.

SUMMARY

The disclosure includes at least an apparatus, a system and method for aprint head for additive manufacturing. The apparatus, system and methodmay include at least two proximate hobs suitable to receive and extrudetherebetween a print material filament for the additive manufacturing,each of the two hobs comprising two opposing halves, wherein each of thehob halves comprises teeth that are offset with respect to the teeth ofthe opposing hob half; a motor capable of imparting a rotation to atleast one of the two hobs, wherein the extrusion results from therotation; and an interface to a hot end capable of outputting the printmaterial filament after at least partial liquification to perform theadditive manufacturing.

Thus, the disclosed embodiments provide an apparatus, system, and methodfor an apparatus, system and method for an additive manufacturing printhead.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed non-limiting embodiments are discussed in relation to thedrawings appended hereto and forming part hereof, wherein like numeralsindicate like elements, and in which:

FIG. 1 is an illustration of an additive manufacturing printer;

FIG. 2 is an illustration of an exemplary additive manufacturing system;

FIGS. 3A and 3B illustrate hobs of an additive manufacturing print head;

FIGS. 4A and 4B illustrate hobs of an additive manufacturing print head;

FIG. 5 illustrates a hob system for an additive manufacturing printhead;

FIGS. 6A and 6B illustrate a servo motor for rotating one or more hobsof an additive manufacturing print head;

FIGS. 7A and 7B illustrate an exemplary hot end feed path in an additivemanufacturing print head;

FIG. 8 illustrates the zoned melting of a hot end in an additivemanufacturing system;

FIG. 9 illustrates a print head in an additive manufacturing system;

FIG. 10 illustrates a print head in an additive manufacturing system;and

FIG. 11 illustrates an exemplary computing system.

DETAILED DESCRIPTION

The figures and descriptions provided herein may have been simplified toillustrate aspects that are relevant for a clear understanding of theherein described apparatuses, systems, and methods, while eliminating,for the purpose of clarity, other aspects that may be found in typicalsimilar devices, systems, and methods. Those of ordinary skill may thusrecognize that other elements and/or operations may be desirable and/ornecessary to implement the devices, systems, and methods describedherein. But because such elements and operations are known in the art,and because they do not facilitate a better understanding of the presentdisclosure, for the sake of brevity a discussion of such elements andoperations may not be provided herein. However, the present disclosureis deemed to nevertheless include all such elements, variations, andmodifications to the described aspects that would be known to those ofordinary skill in the art.

Embodiments are provided throughout so that this disclosure issufficiently thorough and fully conveys the scope of the disclosedembodiments to those who are skilled in the art. Numerous specificdetails are set forth, such as examples of specific components, devices,and methods, to provide a thorough understanding of embodiments of thepresent disclosure. Nevertheless, it will be apparent to those skilledin the art that certain specific disclosed details need not be employed,and that embodiments may be embodied in different forms. As such, theembodiments should not be construed to limit the scope of thedisclosure. As referenced above, in some embodiments, well-knownprocesses, well-known device structures, and well-known technologies maynot be described in detail.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. For example, asused herein, the singular forms “a”, “an” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The steps, processes, and operations described herein are notto be construed as necessarily requiring their respective performance inthe particular order discussed or illustrated, unless specificallyidentified as a preferred or required order of performance. It is alsoto be understood that additional or alternative steps may be employed,in place of or in conjunction with the disclosed aspects.

When an element or layer is referred to as being “on”, “engaged to”,“connected to” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present, unless clearlyindicated otherwise. In contrast, when an element is referred to asbeing “directly on,” “directly engaged to”, “directly connected to” or“directly coupled to” another element or layer, there may be nointervening elements or layers present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between,” “adjacent” versus “directlyadjacent,” etc.). Further, as used herein the term “and/or” includes anyand all combinations of one or more of the associated listed items.

Yet further, although the terms first, second, third, etc. may be usedherein to describe various elements, components, regions, layers and/orsections, these elements, components, regions, layers and/or sectionsshould not be limited by these terms. These terms may be only used todistinguish one element, component, region, layer or section fromanother element, component, region, layer or section. Terms such as“first,” “second,” and other numerical terms when used herein do notimply a sequence or order unless clearly indicated by the context. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of the embodiments.

As discussed herein, improved print head embodiments are sought: inwhich print head speed may be improved without the referenceddetrimental effects, such as lagging or jamming; in which printingprecision may be improved; in which printing responsiveness is improved;and in which weight of the print head is decreased. Print head speed maybe improved in the disclosed embodiments and their equivalents to, forexample, 100 mm³ per second; precision may be improved, such as to0.0003 mm³ per count, with a 10 micrometer trace length resolution at a400 micrometer wide and 100 micrometer thick trace; responsiveness maybe improved, such as to a 1 kHz system response with a 2 microsecondslam stop; and the weight of the print head may be improved, such as toon the order of or less than 600 grams.

FIG. 1 is a block diagram illustrating an exemplary FDM printer 100. Inthe illustration, the printer includes an X-Y axis driver 102 suitableto move the print head 104, and thus the print nozzle 106, in a twodimensional plane, i.e., along the X and Y axes. Further included in theFDM printer 100 for additive manufacturing are the aforementioned printhead 104 and print nozzle 106. As is evident from FIG. 1 , printing mayoccur upon the flow of heated print material outwardly from the printnozzle 106 along a Z axis with respect to the X-Y planar movement of theX-Y driver 102. Thereby, layers of print material 110 may be providedfrom the print nozzle 106 onto the build plate 111 along a path dictatedby the X-Y driver 102.

FIG. 2 illustrates with greater particularity a print head 104 and printnozzle 106 system for an exemplary additive manufacturing device, suchas a 3-D printer, such as a FDM printer. As illustrated, the printmaterial 110 is extruded via hobs 103 of the head 104 from a spool ofprint material 110 a into and through the heated nozzle 106. As theprint nozzle 106 heats the print material 110, the print material 110 isat least partially liquefied for output from an end port 106 a of theprint nozzle 106 at a point along the print nozzle 106 distal from theprint head 104. Thereby, the extruded print material 110 is “printed”outwardly from the end port 106 a via the Z axis along a X-Y planar pathdetermined by the X-Y driver 102 (see FIG. 1 ) connectively associatedwith the print head 104.

The embodiments may provide the foregoing improvements to the print head104 by, among other things, providing improved hobs 103 and hob drivers302 to grip the print material 110 from the print material spool 110 a.FIG. 3 illustrate the “engagement length” 304 of a hob with a printmaterial 110, as those terms are used herein. In the current art, thisengagement length 304 a typically results from hobs having diameters inthe range of 8 to 12 or 15 mm.

The gripping of the print material 110 by hobs 103 having smallerdiameters of 8 to 12 mm, and hence smaller engagement lengths 304 a, isillustrated with respect to FIG. 3A. Certain of the embodiments improvethe engagement length 304 by increasing the engagement surface, that is,by increasing the diameter of the hobs 103 to enhance the engagementlength 304 with the printed material filament 110, as illustrated inFIG. 3B. Such increased diameter hobs 103 may, for example, have adiameter in the 20-40 mm range.

Further and as illustrated in the exemplary embodiments of FIGS. 4A and4B, each hob 103 may have opposing half hob 103 a and 103 b. A series ofteeth 402 a, 402 b may be provided on each hob 103, or on each half hob103 a, 103 b. The teeth 402 a and 402 b may, by way of non-limitingexample, have sharpened surfaces, such as in order to enhance grip onthe print material 110.

In certain embodiments, the teeth 402 a and 402 b of the opposing halfhobs 103 a and 103 b may be offset with respect to one each other by apredetermined offset amount, such as 180 degrees. More particularly,such misalignment may be between 5 degrees and 180 degrees, and mayoccur by sheer random association of the two opposing hob halves 103 aand 103 b. Moreover, the two opposing hob halves 103 a and 103 b may beprovided with a shim therebetween, such that the shim may be selectedbased on the desired grip level to be provided by the hob 103 once thetwo opposing hob halves 103 a and 103 b are joined.

Of note, overly sharpened teeth 402 and 402 b may bite undesirablysignificantly into the print material 110, thereby increasing drag, andas such teeth 402 a and 402 b may be sandblasted, plated, or offset butwith non-sharpened surfaces (such as square or spherical filament gripsurfaces), or offset but with varying teeth shapes (such as varyingbetween triangular, square, and spherical grip surfaces), and so on.

Of course, opposing hob halves 103 a, 103 b may be consistentlymanufactured in the same manner, and thus the teeth 402 a, 402 b may beoffset only upon interconnection of the opposing hob halves 103 a, 103b. Therefore, adjustability, such as an adjustable shim 404, may beprovided between opposing hob halves 103 a, 103 b in order to adjust thegrip level of the hobs 103 onto the print material 110. Increased gripprovided by the hobs 103 may allow for a correspondent decrease in thediameter of the hobs 103 over that referenced above in relation to FIGS.3 , due, in part, to the decreased necessity of an increase inengagement length 304 in light of the enhanced grip. Additionally andalternatively, the number of teeth 402 a and 402 b in each opposing hobhalf 103 a and 103 b may be reduced, but with the teeth 402 stillstaggered, so long as an engagement length 304 along the print material110 maintains a predetermined level of friction in order to meet thecharacteristics discussed throughout.

In accordance with the foregoing, very high levels of grip on printmaterial 110 with very low loss (i.e., drag/friction) may thus providedby certain of the embodiments. Moreover, diameter of the hobs 103 may beadjusted over the known art to vary across print environments to provideonly the necessary level of torque, such as for a given print material110 or a given printing technique. The foregoing may also lead todecreased costs, such as due to the ready replaceability of the hobs103, which may also improve the time needed to clean and service a printhead 104.

FIG. 5 illustrates an exemplary assembly for hobs 103 according tocertain of the embodiments. As illustrated, only the “drive hob” 103-1may be driven in certain of the embodiments, whereas the opposing hob103-2 may be passive, and the driven hob 103-1 may include, inassociation therewith, one or more force adjustments 502 to adjust theforce applied by the hobs 103, such as particularly by the passive hob103-2, to the print material 110. More particularly, the forceadjustment 502 may be provided not only on the non-drive hob 103-2, butadditionally on the driven hob 103-1, or on both hobs.

The non-driven hob 103-2 may be spring loaded, cammed, or otherwisepressed against the driven hob 103-1 to both provide optimal grip of theprint material 110 between the hobs 103 and/or to provide a relativeadjustability to allow for differing filament sizes withoutnecessitating mechanical readjustment of the distance between the hobfilament grip. For example, the force adjustment 502 may include adedicated force adjustment 502 a and/or an open/close cam 502 b that isprovided in association with one of the hobs 103-1 and 103-2. In suchembodiments, when the cam 502 b closes, the hobs 103 are physically moreclosely associated with the print material 110 due to the forcedproximity to one another. An additional or secondary force adjustment502 a may move toward or away from the cam 502 b, such as by arotational adjustment to a threaded adjustable force element 502 a asshown by way of non-limiting example, to thereby press (or depress) thenon-driven hob 103-2 associated with the force adjustment 502 closer toor further from the driven hob 103-1, which necessarily modifies theforce applied by both hobs 103 to the print material 110.

As referenced throughout, a servo motor 602 may be employed to drive thedriven hob(s) 103-1 according to certain of the embodiments, rather thanthe stepper motor of the known art (noting that only one hob may bedriven, as referenced above, while the non-driven hob(s) 103-2 may bespring loaded to apply the requisite force to the print material 110.More specifically, in the known art a stepper motor is typically used todrive the driven hob(s) 103-1, and consequently the typical open loopdrive of a stepper motor continues to drive at the same pace regardlessof slippage, counterforce, or the like. In stark contrast to knownstepper motors, the use of a servo motor 602 in certain of the disclosedembodiments may provide, for example, 500 Hz of servo-mechanical bandwidth, and filament grip may be still further enhanced through the useof a motor encoder in conjunction with the servo motor 602, as discussedfurther herein below. That is, the use of a motor encoder 604 may allowfor monitoring for slippage, motor counterforce, or the like so thatadjustments may be made to maintain a desired and consistent printmaterial 110 feed speed.

Further, the use of a single driven hob 103-1 in conjunction with aservo motor 602 may allow for a direct drive of the driven hob 103-1,i.e., a gearless hob drive (not shown). Although a gearless hob drivemay slightly increase the distance from the center axis of the drivenhob to the mid-melt point, such as to allow sufficient space formounting of the servo motor 602 (which may be direct drive), a gearlessdrive nevertheless further enhances the avoidance of crimping andjamming of the print material 110.

FIGS. 6A and 6B illustrate a servo motor 602 that may, in certain of theembodiments, include one or more motor encoders 604, such as in order toallow for measurement and calibration of the motor drive. Theservo-mechanical coupling provided in the embodiments between the hobs103 and the print nozzle 106 may be appreciably improved over the knownart through the use of an servo motor 602, which may be encoded, whichallows for enhanced feed rate, such as 1 kHz or more, in part due to thehigh torque available due to the improved servo mechanical relationship.

Accordingly, high torque motor drive may be provided in certain of theembodiments. In addition to the torque level, the speed andresponsiveness to torque of the driver motor may be of importance in theembodiments, because, as stated above, it is preferable that the motorbe suitable to quickly provide high torque, and then to quickly ceaseproviding of torque, in order to provide a more refined print control.Suitable motors may include, by way of non-limiting example, a 20 timestorque density motor.

As referenced, a motor encoder 604, such as an integrated magneticencoder, may be provided in association with the hobs 103 and/or theservo motor 602. The providing of a motor encoder 604 provides forenhanced printing resolution and control due to improved motor positionassessment, and thus improved torque control, as will be understood tothose of ordinary skill in the pertinent arts.

In additional and alternative embodiments, one or more of the hobs 103may be conductive. Accordingly, one hob may be provided as an anode,while the material filament may serve as the cathode, or one hob mayserve as the anode while the other hob serves as the cathode.Accordingly, the print material 110 may be electrically heated between acathode and an anode before reaching the hot end, or the print material110 may be charged or otherwise electrified in order to improve adhesionor impart electrical charge to the build, by way of non-limitingexample.

By way of further example and in order to avoid respooling/crimping, thefeed-in may be shimmed 702 in at approximately ˜0.010″ below hobs 103,or may otherwise be presented with a dictated path 704, as illustratedin FIGS. 7A and 7B. The feed hardware in these and others of theembodiments may, by way of non-limiting example, be formed of glass,sapphire, 440C, WC, Al2O3, or ceramic. Moreover, such materials mayfurther serve to minimize crimping or buckling wherever the filamentruns through the feed apparatus, such as at upper and lower receivers,the hobs 103, the feed tube, etc.

An air feed 710 may be provided in association with the print head 104,as is illustrated in FIG. 7B. By way of non-limiting example, this airfeed 710 may be used for: cooling the extruder motor; cooling the hobs;cooling the nozzle.

More particularly, the print head 104 serves the function of extrudingthe print material 110 into the hot end, which includes print nozzle106, at the speed dictated by the rotation of the hobs 103 associatedwith the print head 104. More particularly, it is desirable that theprint head 104 be enabled to go from significant print material 110 feedspeed to zero speed, and from zero to significant print material 110feed speed, readily, as discussed herein throughout. More specificallyand as illustrated in FIG. 8 , the print material 110 is fed by theprint head 104 into the hot end 106 in such a manner that “zones” arecreated within the hot end that includes print nozzle 106 which enablethe discharge of the melted print material 110 from the print port 106 aof the print nozzle 106 of the hot end.

As shown, the print head 104 feeds a solid print material 110 into theupper portion of the hot end, and the heat applied by the hot end to theprint material 110 causes a portion of the print material 110 to meltwithin the hot end. A cone of unmelted print material 110 then occurswithin a solid zone 802 a, and is surrounded by the melted printmaterial 110 in a melt zone 802 b, such that, as long as the unmeltedprint material 110 cone within the solid zone 802 a does notsufficiently penetrate the melt zone 802 b so as to reach the nozzleport 106 a, printing may continue. However, if the speed at which thehobs 103 of the print head 104 feed the print material 110 to the hotend, which includes print nozzle 106, exceeds the melting capabilitiesof the print nozzle 106, the solid zone 802 a of the print material 110will penetrate through the melt zone 802 b and clog the nozzle port 106a. Thereby, a physical and algorithmic association of the servo rate ofrotation of the hobs and the capacity of the hot end to melt the printmaterial 110 for printing may be required in the disclosed embodiments.The algorithmic association may be maintained using one or moreelectrical processors accessing one or more sensors, such as maygenerate data for use in the algorithm regarding the servo motor 602,the motor encoder 604, and so on, as discussed further hereinbelow.

The physical association of the servo motor 602 and the hobs 103 and themelting capacity of the hot end may be managed in a variety of differentways in the embodiments. By way of example and as illustrated in thenon-limiting embodiment of FIG. 9 , the driven hob 103-1 and thenon-driven 103-2 in the disclosed embodiments may be placed appreciablycloser, on center axis, to a center point of the melt zone 802 of thehot end than in the known art. For example, in the known art, a hob'scenter axis may be approximately 400 millimeters from the center of themelt zone, and may, for example, pass through one or more feed tubes. Instark contrast and as illustrated in FIG. 9 , in the disclosedembodiments the center axis of the hob may be approximately 20-40 mm,such as 25 millimeters, from the center point of the melt zone 802.

FIG. 10 illustrates the multiplicative positive effects gained throughthe use of multiple of the disclosed aspects in a single embodiment of aprint head 104. As shown, a feed path 1002 approximately as tall as theprint head 104 may be provided for maximum reduction in print material110 pull. An encoded motor 1004 may be provided so that filament pull,grabbing, jamming, or crimping may be accounted for by adjustment ofmotor speed. A single driven hob 1003 may be provided, and may be matedwith a spring loaded, cammed 1006 non-driven hob 1005 that pressesagainst print material 110 of various sizes.

The illustrated embodiment may provide oversized ones of hobs 1003, 1005to provide optimal horizontal grip length along the filament 1010, andthe driven hob 1003 and the non-driven hob 1005 may each be providedwith teeth 1012, wherein the teeth 1012 may be offset on each hob halfso as to allow for maximum gripping between halves of a single hob andbetween hobs. The feed in 1018 to the hobs may be placed in closeproximity to both the driven hob 1003 and the non-driven hob 1005.Additionally, the feed out 1020 from the head end 104 to the hot end maybe provided very close to the hobs 1003, 1005, such that jamming,buckling, and crimping are prevented. And finally, the center point ofthe melt zone 802 of the hot end may be provided in close proximityalong a lateral distance from a center axis of the driven hob 1003, suchas in order to prevent buckling and jamming.

Moreover, motor 1004 and the controls thereof may be sufficiently fast,powerful, and refined so as to mechanically “oscillate” the filament1010. Oscillation may impart energy to the filament and the melt,thereby enhancing adhesion and/or uniformity upon printing. Oscillationmay additionally help the melt to flow, such as by decreasing thenon-melt zone at the interface with the melt zone as those phrases arediscussed above, and may also help in mixing and/or bonding the meltparticles, such as to allow for the use of multi-filament prints basedon in-melt mixing. Further, heat transfer/coupling to the melt from theheat source may additionally be enhanced by oscillation.

Methodologies of oscillating the filament 1010, in addition to highspeed use or dithering of the motor 1004, may also includeelectromagnetic stimulation or physical vibration of the hot end such asthrough placement of one or more coils about the nozzle 106 of hot endrather than shaking the hot end/nozzle. Exemplary oscillationfrequencies in the embodiments may range from approximately 15 kHz toapproximately 120 kHz.

FIG. 11 depicts an exemplary computing system 1100 for use inassociation with the herein described systems and methods. Computingsystem 1100 is capable of executing software, such as an operatingsystem (OS) and/or one or more computing applications 1190, such asapplications applying the algorithms 104 a discussed herein, and mayexecute such applications, such as to control one or more hob motors bysending data from, and by using data, such as sensor data, received at,the I/O port.

The operation of exemplary computing system 1100 is controlled primarilyby computer readable instructions, such as instructions stored in acomputer readable storage medium, such as hard disk drive (HDD) 1115,optical disk (not shown) such as a CD or DVD, solid state drive (notshown) such as a USB “thumb drive,” or the like. Such instructions maybe executed within central processing unit (CPU) 1110 to cause computingsystem 1100 to perform the operations discussed throughout. In manyknown computer servers, workstations, personal computers, and the like,CPU 1110 is implemented in an integrated circuit called a processor.

It is appreciated that, although exemplary computing system 1100 isshown to comprise a single CPU 1110, such description is merelyillustrative, as computing system 1100 may comprise a plurality of CPUs1110. Additionally, computing system 1100 may exploit the resources ofremote CPUs (not shown), for example, through communications network1170 or some other data communications means.

In operation, CPU 1110 fetches, decodes, and executes instructions froma computer readable storage medium, such as HDD 1115. Such instructionsmay be included in software such as an operating system (OS), executableprograms, and the like. Information, such as computer instructions andother computer readable data, is transferred between components ofcomputing system 1100 via the system's main data-transfer path. The maindata-transfer path may use a system bus architecture 1105, althoughother computer architectures (not shown) can be used, such asarchitectures using serializers and deserializers and crossbar switchesto communicate data between devices over serial communication paths.System bus 1105 may include data lines for sending data, address linesfor sending addresses, and control lines for sending interrupts and foroperating the system bus. Some busses provide bus arbitration thatregulates access to the bus by extension cards, controllers, and CPU1110.

Memory devices coupled to system bus 1105 may include random accessmemory (RAM) 1125 and/or read only memory (ROM) 1130. Such memoriesinclude circuitry that allows information to be stored and retrieved.ROMs 1130 generally contain stored data that cannot be modified. Datastored in RAM 1125 can be read or changed by CPU 1110 or other hardwaredevices. Access to RAM 1125 and/or ROM 1130 may be controlled by memorycontroller 1120. Memory controller 1120 may provide an addresstranslation function that translates virtual addresses into physicaladdresses as instructions are executed. Memory controller 1120 may alsoprovide a memory protection function that isolates processes within thesystem and isolates system processes from user processes. Thus, aprogram running in user mode may normally access only memory mapped byits own process virtual address space; in such instances, the programcannot access memory within another process' virtual address spaceunless memory sharing between the processes has been set up.

In addition, computing system 1100 may contain peripheral communicationsbus 135, which is responsible for communicating instructions from CPU1110 to, and/or receiving data from, peripherals, such as peripherals1140, 1145, and 1150, which may include printers, keyboards, and/or thesensors, encoders, and the like discussed herein throughout. An exampleof a peripheral bus is the Peripheral Component Interconnect (PCI) bus.

Display 1160, which is controlled by display controller 1155, may beused to display visual output and/or presentation generated by or at therequest of computing system 1100, responsive to operation of theaforementioned computing program. Such visual output may include text,graphics, animated graphics, and/or video, for example. Display 1160 maybe implemented with a CRT-based video display, an LCD or LED-baseddisplay, a gas plasma-based flat-panel display, a touch-panel display,or the like. Display controller 1155 includes electronic componentsrequired to generate a video signal that is sent to display 1160.

Further, computing system 1100 may contain network adapter 1165 whichmay be used to couple computing system 1100 to external communicationnetwork 1170, which may include or provide access to the Internet, anintranet, an extranet, or the like. Communications network 1170 mayprovide user access for computing system 1100 with means ofcommunicating and transferring software and information electronically.Additionally, communications network 1170 may provide for distributedprocessing, which involves several computers and the sharing ofworkloads or cooperative efforts in performing a task. It is appreciatedthat the network connections shown are exemplary and other means ofestablishing communications links between computing system 1100 andremote users may be used.

Network adaptor 1165 may communicate to and from network 1170 using anyavailable wired or wireless technologies. Such technologies may include,by way of non-limiting example, cellular, Wi-Fi, Bluetooth, infrared, orthe like.

It is appreciated that exemplary computing system 1100 is merelyillustrative of a computing environment in which the herein describedsystems and methods may operate, and does not limit the implementationof the herein described systems and methods in computing environmentshaving differing components and configurations. That is to say, theconcepts described herein may be implemented in various computingenvironments using various components and configurations.

In the foregoing detailed description, it may be that various featuresare grouped together in individual embodiments for the purpose ofbrevity in the disclosure. This method of disclosure is not to beinterpreted as reflecting an intention that any subsequently claimedembodiments require more features than are expressly recited.

Further, the descriptions of the disclosure are provided to enable anyperson skilled in the art to make or use the disclosed embodiments.Various modifications to the disclosure will be readily apparent tothose skilled in the art, and the generic principles defined herein maybe applied to other variations without departing from the spirit orscope of the disclosure. Thus, the disclosure is not intended to belimited to the examples and designs described herein, but rather is tobe accorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A print head used for additive manufacturingusing a print filament, comprising: a nozzle having an interior chamberextending between first and second longitudinal ends thereof andproviding a melt zone therein, wherein the print filament is fed intothe first longitudinal end of the nozzle, then into the interior chamberwhere it is heated in the melt zone, and is then extruded from thesecond longitudinal end of the nozzle; two proximate hobs suitable toreceive and feed therebetween into the first longitudinal end the printfilament for the additive manufacturing, each of the two hobs having anengagement length correspondent to a diameter of each hob in a range of20 mm-40 mm, and each of the two hobs comprising two sets of teeth alongthe engagement length, the two sets of teeth being offset with respectto each other; and a motor capable of imparting a rotation to at leastone of the two hobs, wherein the extrusion results from the rotation. 2.The printhead of claim 1, wherein the motor comprises a servo motorhaving a shaft connected to one of the two hobs to directly impart therotation thereon.
 3. The printhead of claim 1, further comprising a shimbetween each pair of the hob halves to provide a predetermined griplevel by the two hobs on the filament.
 4. The printhead of claim 1,wherein a feed rate from the two hobs to the interior chamber comprisesa 1 kHz response time with a 2 microsecond slam stop.
 5. The printheadof claim 1, wherein the teeth comprise sharpened surfaces.
 6. Theprinthead of claim 1, wherein a lateral distance from a center axis ofthe hobs to a midpoint of the melt zone is approximately 25 millimeters.7. The print head of claim 1, further comprising at least one encoderassociated with the motor.
 8. A print head for additive manufacturingusing print filament, comprising: a nozzle having an interior chamberextending between first and second longitudinal ends thereof andproviding a melt zone therein, wherein the print filament is fed intothe first longitudinal end of the nozzle and then into the interiorchamber, is heated in the melt zone, and is extruded from the secondlongitudinal end of the nozzle; two proximate hobs suitable to receiveand feed therebetween into the first longitudinal end the print filamentfor the additive manufacturing, each of the two hobs comprising twoopposing halves, wherein each of the respective hob's two halvescomprises teeth that are offset with respect to the teeth of theopposing hob half by between 5 and 180 degrees; and a motor capable ofimparting a rotation to at least one of the two hobs, wherein theextrusion results from the rotation.
 9. The printhead of claim 8,wherein the two proximate hobs each have a diameter of about 20 mm. 10.The printhead of claim 8, wherein the two hobs each have a diameter in arange of 20-40 mm.
 11. The printhead of claim 8, wherein the motorrotates one of the two hobs, and the hob not rotated by the motorcomprises the at least one force adjustable threaded force element. 12.The printhead of claim 11, wherein the at least one adjustable threadedforce element further comprises a spring loaded cam associated with arotatable distance adjustment.
 13. The printhead of claim 8, furthercomprising an air feed for cooling.
 14. The printhead of claim 8,wherein a lateral distance from a center axis of the hobs to a midpointof the melt zone is approximately 25 millimeters.
 15. The printhead ofclaim 14, further comprising at least one sensor that senses at leastone of the motor, the hobs and the second longitudinal end.
 16. A printhead for additive manufacturing using print filament, comprising: anozzle having an interior chamber extending between first and secondlongitudinal ends thereof and providing a melt zone therein, wherein theprint filament is fed into the first longitudinal end of the nozzle andthen into the interior chamber, is heated in the melt zone, and isextruded from the second longitudinal end of the nozzle; two proximatehobs suitable to receive and feed therebetween into the firstlongitudinal end the print filament for the additive manufacturing, eachof the two hobs comprising two opposing halves, wherein each of therespective hob's two halves comprises teeth that are offset with respectto the teeth of the opposing hob half and which vary in shape betweentriangular, square and spherical; and a motor capable of imparting arotation to at least one of the two hobs, wherein the extrusion resultsfrom the rotation.
 17. The printhead of claim 16, wherein the motorcomprises a servo motor having a shaft connected to one of the two hobsto directly impart the rotation thereon.
 18. The printhead of claim 16,wherein the two hobs each have a diameter in a range of 20-40 mm. 19.The printhead of claim 16, wherein the teeth comprise sharpenedsurfaces.
 20. The printhead of claim 16, wherein the teeth comprisenon-sharpened surfaces.